


You, W.D. Dadster, and .... a baby?

by The_Fallen_Human (orphan_account)



Series: Undertale Sinner Trash Pregnancies [1]
Category: Undertale (Video Game)
Genre: F/M, I don't know how tags work, Morning Sickness?, Of sorts?, Pregnancy, Pregnant Reader, Reader-Insert, Trash Fic, im absolute trash, like me, sinner trash, sinner trash fic, this is for you sinner trash, trash
Language: English
Status: In-Progress
Published: 2016-03-01
Updated: 2016-03-25
Packaged: 2018-05-24 04:24:39
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 3,018
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6141397
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/The_Fallen_Human
Summary: <blockquote class="userstuff">
              <p>I'm such a sinner. Please help.<br/>As promised, I am writing a story. This is my first work I've posted on here. This the first of a series of stories I'm writing.</p>
            </blockquote>





	1. The Bathroom and Some Sickness

**Author's Note:**

> This started out because of some comment which turned into a what if? Like what if the reader got pregnant during one of these reader insert fics when they do the sin with Gaster?

You were knelt down over the toilet, nauseated. There goes your dinner. The food wasn't spoiled or anything--- maybe the expiration label was wrong on that jar? Unlikely but possible. You attempted to steady yourself away from the toilet to try to stand up to try to get to bed. Instead you manage to shift your position and put your knees up near your chest while leaning against the wall.

You hugged your knees and slowly let yourself fall sideways onto the bathroom floor, the cold tile pressed against your cheek. You probably shouldn't be laying down here like this, but you didn't have the energy to do anything else movement wise. You shuddered against the cold tile that was pressed against your face, the exposed parts of your body that weren't protected by your pajamas were becoming colder and colder. If you kept this up, you could catch a cold.

You were tired, more tired than usual these last few days. You couldn't quite put your finger on why, you just were. Thank goodness you had finished all your classes and graduated a month ago. There's no way you would have been able to attend class like this. The room around you started to grow hazy and the world began to slowly dim to darkness. 

You stirred slightly when you thought you felt something lift you up in your sleep. However you couldn't quite register how before the darkness of sleep pulled you in again. When you started to stir again, you felt comfortable and warm. You felt something cold, like a wet rag wiping off your face. As much as you wanted to ignore that and return to your slumber, you attempted to move one of your arms to find that you were under the covers. You fell asleep in the bathroom, how did you end up back on your bed?

You slowly opened your eyes to see a figure kneeling down at your bedside. You couldn't quite tell who it was as your vision was still blurry, leading you to blink a few more times. You smiled a little as you saw who the figure was. You guessed he couldn't just stay away and observe you when you were sick like this.

Gaster.


	2. Examination

**Summary for the Chapter:**

> I can't believe I let this get out hand when writing, this was supposed to be something short but now look at what I've done.

{Are you alright, y/n?} a familiar voice asked.

 

“No… Not really.” You answered truthfully. 

 

You felt sore, your muscles felt like you had been working out for a couple days straight without rest. You were drained, unnaturally tired. You had no will to get up out of bed, I fact the only reason you were in the bathroom was because you had to force every fiber of your being to get up to create a little bit of determination. If you were on Shark Week, the monthly curse, your bedsheets and pajamas would be an absolute mess. You could barely keep your eyes open to look at Dr. Gaster, your boyfriend--- no unofficial life partner of sorts.

 

{May I examine your soul?} The skeleton void being asked. 

 

“Why?” You asked, confused at why he would need to see your soul.

 

{Because, the aura your soul emits isn't as strong as it normally is, and I suspect something is amiss.} The void scientist answered with concern laced in the tone of voice.

 

That made perfect sense. Your reaction to his explanation echoed in your mind. You would have said out loud for him to hear but you did not, your body seemed not to want to listen to you anymore today.

 

You gave him a weak nod. “Alright…. Go ahead.” You muttered weakly.

 

The doctor nodded in response and removed the bedsheets from your body. before placing his hand over your chest. You shivered at the sudden cold air that now surrounded your body, you looked at the void scientist doctor hand to distract you from the cold, not wanting your shivering to disturb anything. His fingers were skeletal but his palm looked more like the shape of a human palm made of bone, minus the hole in the palm side. He let his hand hover there for a few moments to allow you to prepare yourself for the sensation. Gaster had done this plenty of times before and he always gave you a moment to prepare before he removed your soul. This time however, he waited a minute or two before using his magic to reach for your soul. You closed your eyes, trying to sort out an explanation for this. Why was he hesitating? What was making this different from before?---

 

Your eyes immediately shot open at the sudden sensation of pain.

 

You wanted to thrash and scream as your soul was being removed from your body. This was different, every other time Doctor Gaster had done this, it was quick and painless. This time was the exact opposite. Something within the pit of your abdomen felt like it was being pulled into a knot when he was trying to remove your soul. This was worse than the worst pain you had felt because of a stomach pain of any kind or any cramp caused by shark week you could ever remember. You kicked weakly at the empty space in front of you in the bed, unable to find the strength to do anything else in terms of thrashing. Gaster ignored your kicking and continued. The good doctor furrowed his nonexistent eyebrows, this was not a result he was expecting. Gaster slid his free hand under your shirt and placed it on your abdomen and began to release some sort of magic energy into your abdomen. 

 

Why would he need to do that? You mentally asked yourself before suddenly something made a little bit of sense.

 

The magic he released was immediately absorbed by your body and the pain you were feeling was no longer very painful, the knot that your insides were pulling itself into began to unravel. The pull your abdomen had on your soul was greatly relaxed. The pull was still there, but instead of the taut pull and iron grip, it was comparable to a string that was very slack that was connected to your soul. You stopped kicking at the empty space in front of you, no longer in pain.

 

When your soul finally did emerge, you could see how weak it looked. The normal (y/sc) heart shaped gem nearly looked translucent, you could see right through it. Gaster frowned at the condition your soul was in before releasing more magic into your abdomen and color returned to your soul, with that, you felt less drained. His concerned expression softened a little at this result of this.The white pin prick pupils in his eye sockets still flared with concern as a purple glow around them due to the use of his magic. However, this glow flared a bit in excitement for some reason, which confused you greatly. The former royal scientist gently used his magic to place your soul back in your chest. 

 

The purple glow around the doctor’s pupils disappeared as he stopped using his magic. Gaster then looked at you directly with his expression full of concern but holding a hint of excitement. You weren't sure what to make of this.

{y/n.....}

Wait. What?


	3. Revelation

Wait.   
What?

 

“I'm what?” You asked him, not believing the words you just heard.

 

{You're pregnant.}

 

How was that even possible? It wasn't possible. 

 

“Impossible.” You said, you were trying to convince yourself that this was a joke of some sorts on his part to try to lighten your mood.

 

Gaster frowned and continued to look at you with a serious expression. When his expression continued to stay the same, you finally relented to the fact he was not joking at all. Your mood instantaneously dropped and you frowned at him. He lied to you! He lied!

 

“You lied to me!” You exclaimed at him. “You said you couldn't get me pregnant!”

 

{I said never said such a thing.} The void scientist shook his head. “I never said such a thing.”

 

You grumbled angrily under your breath. Gaster was right, he never said it was impossible. You wanted to scream so loudly. You've never heard about pregnancies that have happened as a result of monster and human copulation before, monsters were still a recent thing, despite of the fact it has been two years. How would you explain this to your friends--- well you weren't too worried about explaining it to your friends, in fact one of them is dating a monster bartender made of fire, and your social group of friends are very accepting of your friend’s relationship and your own relationship.

 

The real concern was going to be telling your parents about this. Your parents were very skeptical about monsters and didn't trust them,. In fact, you never told them about your relationship with Gaster. You had explained to Gaster about your parents and he agreed that it would be best not to tell them of your relationship, as they were likely to take it negatively and overreact. You sighed before sitting up and burying your face in your hands.

 

{What's wrong, y/n?} Gaster asked in a soft voice, careful to not accidentally upset you further.

 

“This is frustrating.” You answered bluntly before realizing what you said. “Not the pregnancy part but it brings frustrating things into the mix. How am I going to tell my parents? What if my parents want to see the baby after the they’re born and they realize---” You explained before your thoughts started to trail off.

 

Gaster nodded understandingly as his expression changed to a more solemn one. He furrowed his nonexistent eyebrows. The former royal scientist was happy and excited that he was having a child with you but the full complexities were now occurring to him. Your parents and their opinion regarding monsters was one of those complexities.

{Yes…. As exciting and great as this might be, the problems that will undoubtedly arise due to your parents is very concerning.} He said before standing up from the position he was in. Gaster had still been kneeling down by your side this entire time.

 

The scientist walked over to the other side of your bed and laid down besides you. He propped himself up against some pillows. Gaster sighed a bit, feeling the stress of all the things that needed to be taken care of and solved due to this turn of events. 

 

What also troubled the scientist was how sick you had gotten and how your soul was being drained of energy during this process. Monster souls were made of magic, and most humans possessed very little magic and because of this, it had taken a toll on you. It was only when he transferred some of his magic to the unborn child directly you recovered most of your strength. He was going to have to have to directly transfer magic to you and the child to keep you and the unborn child healthy on a regular basis. This shouldn't be too much of a problem however. The fact that this was less concerning than your parents’ reaction is a bit bothersome. 

 

Gaster watched you close your eyes shut as you yawned. He began to run his bony fingers through your hair gently. He paused in his affections as you relaxed and shifted back down in a laying position. 

 

Exhaustion claimed your mind as the events of today played in your thoughts like a movie. Your breathing began to slow as your mind slowly drifted into the dreamscape world of sleep.

 

Gaster laid next to you. As a monster tainted by the void, he did not need sleep. But instead of going to work on any of the experiments he had, the doctor thought it would be best if he stayed here with you, in case you started to get ill like you had been not too long ago. Your health was more important than any experiment that he had been working on. Gaster refused to let science get in the way of the health of you and the unborn child.

 

Gaster looked at you and smiled softly. 

 

{Sweet dreams, y/n.}

**Notes for the Chapter:**

> Confiteor Akatosh Sancto.   
> Ad magna Talos iusti semper.   
> Ad fortium ascendit Reman.   
> Ad Sanctum Novem.   
> Et omnibus Sanctis.   
> \------  
> If you get the references for the song and what I've done to edit it--- .... Uhh I'll do something? I'm not sure.


	4. Chapter 4

**Summary for the Chapter:**

> I don't know what I was writing. I started on writing this a few weeks ago. Then I reopened it again today and just started writing.

**Notes for the Chapter:**

> My dad is making me watch a play released in the 70's about Jesus and I don't want to watch it. Ugh.

Gaster was reluctant to leave you alone for too long. The unborn child was not just going to be a monster-human hybrid but a monster-human and void being hybrid. He would need to transfer some of his magic that was tainted with the void every few hours to keep you from getting sick. But he didn't want to risk any possible unforeseen complications with you or the unborn child. You were surprised when he insisted you join him in his lab down in the basement. Which brings you to the current situation at hand. 

 

You are now laying down on an examination table under an examination lamp. The room was painted a dark shade of gray. It was always unbelievably cold down here, the entire atmosphere of the room made it worse. The hospital gown you were wearing was not doing much in the way of keeping you warm. You shivered a little, your teeth chattering together.

 

“Could you at least turn on the heat, or give me a blanket?” You whined.

 

It seemed he didn't hear you. He was probably too absorbed in his work to notice. You could try to stand up and leave but he would definitely hear you staggering towards the door that lead to the stairway. You groaned in frustration and shut your eyes when suddenly you felt something soft and warm drape over your body. You opened your eyes to see a warm heating blanket over your cold body. Gaster was standing next to the examination, holding something, you couldn't make out what. You purred in contentment as you snuggled to get comfortable. 

 

“I would be a terrible father if I let the unborn child and their mother freeze to death.” Gaster chuckled. “It would be such a waste of all potential scientific and medical breakthroughs that would be brought by the child being born.”

 

“Shut up!” You said before giggling a little at the fact he managed to turn his statement into something more professional.

 

“Lift your head up.” The scientist statedly calmly. 

 

You did so without hesitation and he slipped something under your head. Then Gaster gave you a reassuring look of sorts that you could lay your head back down. You gave yourself area seconds before gently laying your head back down, finding something plush and soft against the back of your head. It was a pillow. How thoughtful. 

 

You closed your eyes and let yourself relax.  
\-----------------

Gaster watched as you closed your eyes and waited a few moments. Once he was certain you were snoring, he went back to another part of the lab to continue some of his other projects that needed attending to. Not that you weren't important but that was more personal than professional. The sensors in the room would alert him of anything.

 

__________________________

 

Your consciousness awakens in a black void. It was empty space. You looked at your hands and legs to make sure they were there on your dream self. They were still there. You floated and floated…. Why were you here? What was this place? Was this the void that Gaster spoke about? If so, why were you visiting it in your dream? You would ask him that later, once you woke up. This seemed to be awfully realistic for a dream as you seemed to be aware of everything; the bitter cold of this place, the lack of light and how desolate it all looked… not only that but the deafening amount silence there was in this place. 

 

You floated for a little while longer before there was a tugging sensation at your soul originating from outside your chest. While this wasn't enough to wake you up completely, it suddenly changed the atmosphere into something more dream like and less realistic. The higher part of your mind began to forget that this was a dream as you were lulled into the normal pattern of dreaming.

_______

Gaster sighed in relief as he stood over your unconscious body. He was worried that reaching for your soul wouldn't have worked. If it hadn't have, your soul would have been trapped in the Void. Could this have been the work of the unborn child that was maturing in your womb? It seemed to be very likely as all evidence pointed to that notion. That was worrisome.

 

Gaster paced back and forth across the room as he began to map out a potential solution to this unforeseen dangerous factor with possibly disastrous consequences. This needed to be dealt with as soon as possible. All other projects of his would be temporarily suspended until this issue was solved.

 

Gaster quickly left the examination room to begin working on a device to suppress the magic of the growing hybrid. He might need to adjust it so the hybrid could continue to use magic to develop and grow. Gaster took no time in going into another room and beginning to draw blueprints for the device he had been planning in his head for the last several minutes. Gaster hated to rush on anything he was working on, so the fact he had to rush to finish this was quite irritating. However, he could not let this agitation get to him. This was more important than any of his other projects combined.

 

Erasing and redrafting in a meticulous manner to try to draft something that would work when he built it. This cycle of erasing and drafting was rather tedious. Gaster crumbled up the paper he had been working on before tossing it into the recycling bin. He began to draft once again, paying more attention to his design details as he drafted, trying not to let the urgency of this situation cloud his mind with anxiety. He needed to keep a level head during all of this excitement. What he needed to build needed to be of the highest quality, no compromises.

**Notes for the Chapter:**

> I need to figure out where I'm going with this story.

**Author's Note:**

> God have MERCY on me.  
> Sithis have MERCY.  
> Asgore have MERCY.  
> .....  
> SOMEONE HAVE MERCY ON MY SOUL.


End file.
